Protective container for electronic assemblies



Aug. 9, 1950 K. E. WOODWARD 2,948,126

PROTECTIVE CONTAINER FOR ELECTRONIC ASSEMBLIES Filed Sept. 3, 1959- IN,p

INVENTOR AENNETH Wooomeo PROTECTIVE CONTAINER FOR ELECTRONIC ASSEMBLIESKenneth E. Woodward, McLean, Va, assignor to the United States ofAmerica as represented by the Secretary of the Army Filed Sept. 3, 1959,Ser. No. 838,004

2 Claims. (Cl. 62-316) (Granted under Title 35, US. Code (1952), sec.266) The invention described herein may be manufactured and used by orfor the Government for governmental pur-- poses without the payment tome of any royalty thereon.

This invention relates to a novel protective container for theprotectionof electronic components or assemblies used in guided missiles fromharmful environmental effects such as shock, vibration, noise, and hightemperatures. The invention provides superior protection of guidedmissile electronic equipment during storage and handling, as well asunder the very severe conditions en countered during missile flight.

While known prior art packaging units or containers may protect theelectronic component against any one of these conditions, these systemsdo not package the electronic components so that they simultaneouslycontrol and minimize the effect of all these environmental conditions.

It is the object of this invention, therefore, to provide a containerwhich will ensure that electronic components are properly isolated fromvibration and noise; that shocks impinging on the package are filteredof damaging highfrequency components, shaped into simple waveforms andprevented from being excessively amplified; and that high internally orexternally generated temperatures will be reduced and positivelycontrolled.

The specific nature of the invention, as well as other objects, uses andadvantages thereof, will clearly appear from the following descriptionand from the accompanying drawing, in which:

Fig. 1 is a side view of the packaging unit of this invention, onequarter of the unit being shown in section.

Fig. 2 a perspective view of the packaging unit of Fig. 1 taken throughlines 22.

As shown in Figs. 1 and 2, container consists of outer and inner casings12 and 13, respectively. Outer casing 12 is designed to be fixed bybrackets 11 (Fig. 1) or by any other suitable means to the inside of thebody of any missile (not shown).

Outer casing 12 comprises a pair of flat circular end plates 14 and ahollow cylindrical shell 15. Shell 15 is provided with outwardlyextending flanges 18 at both ends. Flanges 18 are cut with annular slots22 of rectangular cross-section into which O-rings 24 are tightlypressed. Flat plates 14 are fixed by machine screws 20 to flanges 18, asshown.

Inner casing 13, like outer casing 12, consists of a hollow cylindricalshell 17 and a pair of flat circular end plates 16 which are fastened byscrews 21 to inwardly extending flanges 19. Flanges 19, like flanges 18,are provided with annular slots 23 into which O-n'ngs 25 can be tightlypressed. Electronic components which are required in the missile aremounted to the inside of inner cylinder 13.

Outer casing 12 is separated from inner casing 13 by circularangle-shaped resilient rings 28. Rings 28 act as a spring and causeinner casing 13 to resonate at a frenited States Patent quencydetermined by the stiffness of the spring. A spring material found to besatisfactory is silicone rubber. Also positioned between outer casing 12and inner casing 13 is a cylindrical sleeve 27 composed of acompressible cellular material possessing good damping characteristics.The purpose of this material is to control the amplitudes of innercasing 13 when casing 13 is vibrated at resonance by shock, vibration ornoise. A material which has been found satisfactory for this purposeconsists of polyurethane foam. Circular flat plates 26 are shaped substantially as plates 14 and 16 and are also composed of polyurethanefoam. Any other materials possessing characteristics similar to siliconerubber and polyurethane foam could be substituted for these.

Cylindrical sleeve 27 and end plates 26 are partially saturated with. anevaporative coolant. The degree of saturation depends on the amount ofheat input anticipated in service; A preferred evaporative coolantconsists of a 40% to 60% methanol alcohol-water mixture. Any coolanthaving large specific heats and suitable freezing and boiling pointscould also be used.

When the outer casing 12 experiences a high temperature as a result ofmissile flight, the methanol alcoholwater mixture will evaporate and inevaporating will keep inner casing 13 at a controlled and substantiallyconstant temperature during the flight of the missile.

Escape vents 36 formed in shell 15 allow the evaporating cooling fluidto escape from between casing 12 and casing 13. Circular angleshapeddamping ports 34 formed between angle-shaped rings 28, end plates 16 andshell 17, allow the evaporating coolant to escape to vents 36 fromplates 26 and sleeve 27. Damping ports 34 trap air between plates 26 andsleeve 27. This trapped air dampens the amplitudes of inner casing 13when casing 13 is vibrating at resonance as a result of missilevibration.

O-rings 24 and 25 is slots 22 and 23, respectively, ensure that themixture of methanol alcohol and water will not leak out from between theend plates 14 and 16 and shells 15 and 17.

A feed-through connection 30 prov-ides a means for hermetically sealingthe electronic components (not shown) which are housed in inner casing13 from the environment surrounding outer casing 12. Connection 30consists of two substantially cylindrical elements 31 which areinternally threaded so that inserts 32 can be screwed into elements 31.Inserts 32 are designed to press the flared ends of hollow sleeve 33against the tapered sides of elements 31 as shown in Figs. 1 and 2.Sleeve 33 is composed of a flexible material such as synthetic rubber.Electrical wiring (not shown) which connects the electrical componentshoused in inner casing 13 to other circuits in the missile will passthrough bore 32a formed in insert 32 and in sleeve 33. The wiring whenpositioned in bore 32 can be sealed in bore 32a by any suitable resin orrubber seal. Thus, all the electronic components housed in inner casing1-3 are hermetically sealed therein. I

As described above, high temperatures received by outer casing 12 willcause evaporation of the alcohol coolant mixture absorbed in plates 26and sleeve 27. This will ensure that the outermost surface of innercasing 13 remains at a substantially constant temperature regardless ofthe temperature reached by outer casing 12.

Plates 26 and sleeve 27 also dampen out the detrimental eifects ofnoise, which is ordinarily produced by missile flight. If great noiseattenuation is required, plates 26 and sleeve 27 should contain littleor no coolant. The coolant mixture of methanol alcohol and water can beapplied to the package 10 by placing a cylindrical sleeve of absorbentmaterial containing the coolant mixture around the periphery of shell 15in the same manner as sleeve 27 is wrapped around shell '17. Or,thecooling fluid could be placed in a hollow cylindrical shell or jacketencasing container 10 so that outer casing 12 is immersed completely inthe fluid. In most instances, the system shown in Figs. land 2 willdampen out noise ordinarily encountered during missile operation.

Whencontainer 10 is positioned properly inside the missile gbody-inneneasing 1-3 will cooperate-With 'the spring and damping materials,26 and 27, respectively, so that detrimental vibration and noise areisolated from the electronic components mounted in inner casing 13 andshockimpinging on outer casing '12 are filtered of damaginghigh-frequency components, shaped in-tosimple waveforms and preventedfrom being amplified. The resilience of rings 28 isolates vibration andnoise and filters,- shapes and controls shock. The damping material ofpolyurethane foam in plates 26; and sleeve 2-7 prevents inner casing13from vibrating with uncontrolled amplitudes at resonance.

While casings 12 and 1-3 have been described as cylindrical, they mayalso have other shapes. For example, casings -12 andp13 may be in theshape of hollow cubes in Which case the polyurethane damping materialtherebetween would consist of a hollow square sleeve and two squareends.

It will be apparent that the embodiment shown is only exemplary and thatvarious modifications can be made in construction and arrangement thescope of the invention as defined in the appended claims.

I claim as my invention:

1. A container for housing electronic components comprising: first andsecond hollow cylinders, said first cylinder being encased in:saidseeond cylinder, the longitudinal axis of said first cylinder beingsubstantially coaxial to the longitudinal axis ofsaid-second cylinder, asubstantially cylindrical'member positioned between aid fir n se oncylinder s d m m r onsistin of a spongy cellular-.rnaterial and apair ofresilient rings, said rings forming the corners of said member, saidmaterial being partially ,impregnated, with, an evaporative coolantliquid, and vents in said first cylinder for permitting the escape of.coolant gas therethrough.

2, The container as recited in claim 1 in which said rings are composedof silicone rubber.

Saltzman Sept. 1, 1959

